Combined



(No Model.)

T. B. DOOLITTLE.

COMBINED ANNUNGIATOR AND SPRING JAoK.

W 7T/66.366. 17m/enf@ Unire Sienne Artnr rrrCn..

THOHAS B. DOOLITTLE, OF BRIDGEPORT, COXNEGTICUT.

SPCFICATCN forming part of Letters Patent No. 339,627, dated April 13, 1886.

Application filed November QS, 1385. Serial No. 184,141. (No model.) y

To all nf-71cm it may obli/cern:

Be it known that I, THOMAS B. DooLrrrLn, residing at Bridgeport, in the county of Fairlield and State oi' Connecticut, have invented certain Improvements in a Combined Annunciator and Spring-Jack, of which the following is a speciiication.

My invention relates to an instrument for use in telephone-exchanges; vand it consists of the combination of a switch or springjaclr and an indicating-instrument or annunoiator.

The object ol" my invention is to make a combination-instrument susceptible of adaptation to any of the various arrangements of circuits which are assembled to constitute a telephone-exchange. The instrument embodies all requisite central-office equipment for a single circuit and a series of such instruments or units7 form a centralottice switchboard.

An important feature of my improvement consists in so arranging the instrument that the circuit of which it normally forms part may be readily connected or disconnected with it. For this purpose I provide two in sulated plug-sockets, which are placed in the i'raine oi' the instrument, and at which the electrical connections of the said instrument terminate. These sockets are each provided with a female screw to receive the male screw formed upon the end of a llexible cord-tip, which forms the terminal of a line-wire. If the instrument is to be used upon a metallic circuit, the cord-tips forming the terminals thereof are placed in position in the two insulated sockets respectively; if upon a ground return-circuit the line-wire cord-tip is con! nectcd to one insulated socket and a groundwire cord-tip to the other. In case of metallic circuits where one side or half of the circuit becomes injured or defective, a single wire may thus be readily substituted for the dainaged portion.- rlhe necessity for rejecting the whole circuit is thereby avoided. This improvement Vfacilitates the adaptation of the instrumcnt to use upon any circuit.

In some telephone-exchange systems the annunciator is retained in the circuit during the process of oral communication to serve the purpose of a clearing-out drop. In other systems it is excluded from circuit.

My combination-instrument is so arranged and constructed that either system may be used, the change from one to the other only requiring a single easily-executed variation in the electrical connections of the instrument, which may be readily made without the use of special tools.

The spring-jack plugs, for use with flexible conducting-cords having either one or two conductors, are of improved construction. Heretofore such plugs have been employed; but they have been of such a construction that thejunction between the end ol' the flexible conductor and the contact-point of the plug was necessarily soldered, twisted, or wrapped, and in case of double conductor-cords there frequently occurred a cross or short circuit inside the plug-handle where the insulation ofthe flexible conductors was removed.

In my improved forni of plug I provide a p( ssage in the plug-handle to receive the end i' the conductor, which'passage communicates with the contact-point oi' the pluO. At the junction between this passage and the contact-point there is a screw, which may be separate and independent, or may be formed ol' independently-movable portions of the plug, the end of the liexible conductor being placed under this screw. The said screw or screw connected parts are screwed firmly down, thus securely holding the conductor in electrical contact with the plug terminal or tip. IWhere the plug is for use upon a double conducting-cord, two passages are provided extending longitudinally through the handle, but separate and independent, insulated from each other and terminating` at the respective contact-points of the plug, where screws having bearings in the handle, are provided to hold the condnoter-terminals in secure electrical contact with the contact-points of the plug respectively. In the double contactplug one contact-point is a metal rod placed within but insulated from a metal tube fornin ing the other contact-point. The former projects slightly beyond the latter to make contact with the separable contact-points in the springjaclc.

Referring to the accompanying sheet of drawings, Figure lis a view oi'tlieinstrument complete, with plugs in position. Figs. 2, 3, 4, and show modiiications in the electrical connections, designed to adapt the instrument to various exchange systems. Figs. 6 and 7 ICO are the double and single contact-spring jackplugs-respectively, embodying the improved features above described.

F is a metal frame upon which the parts are secured. Upon its front face is hinged ath an annunciator-drop, A.

m is-an electro-magnet having polar extensions of well-known form. An armature, B,is pivoted at the rear of the frame, its free end being hooked at n to hold the drop A in position, while said armature retains its normal or retracted position.

`a is a flexible spring or electrical contactpoint, making electrical connection with spring b. Both points are insulated from frame F by the rubber plate z'. The free end ofais so placed with respect to the plug socket or opening q in the frame F, that the point of ajackplug inserted in q will raise spring c from its resting position on b.

At the rear right-angled extension of frame F there are two insulated metal plug-sockets, j and lc. These sockets are intended to receive the plugs p, which form the terminals of main lines. l The sockets are preferably screwthreaded to receive a screw-thread upon the end of a cord-tip. By this means the possibility ofthe loosening or disconnection ofthe plug is obviated.

It' it is desired to use the instrument on a single ground return-line, the plug p forming the terminal of that line is inserted in socket j, and a plug, p, connected to earth, is placed in k. If it is desired toplace -the instrument upon a metallic circuit, the plugsp forming the terminals of the direct and return conductor, respectively,are placed in the sockets j and k. The benefit derived from this arrangement will be seen when, for instance, one side of the metallic circuit is broken or becomes in any way defective. The defective portion may be readily removed by withdrawing its plug, and another wire may be substituted by inserting the proper plug. The socket q for the spring jack-plug will receive the double plug P, Fig. 6, or the single plug I, Fig. 7.

In Fig. 6 the double contact-plug l? is for use on metallic circuits, and consists of an insulating-handle, Z, longitudinally perforated with two distinct and separate passages for the two conductors. tis a metal contact-point to connect with the plugA socket g ofthe jack-- frame. It is longitudinally perforated, and a rod of metal, t', forming the second contact, designed to engage with spring a, is fixed within t, but insulated therefrom, as by hard rubber r. The inner ends of these two contactpoints terminate in the two longitudinal passages in the handle respectively. Screws s and s are located at this junction in position to screw down upon and hold the end of flexible conductors, introduced through thelongitudinal passages in the handle, in electrical contact with the respective contact-points.

In Fig. 7 the single conductor-plug P is composed of an insulating-handle, I, longitudinally perforated, a metal contact-point, T, and a screw, S, also-longitudinally perforated and placed within the handle, through which the conductor is passed to the junction between the passage or perforation and the plugtip, where the screw S is screwed down upon and holds said conductor in electrical contact withA the tip T.

The electrical connections of this instrument and the variations therein provided for in the construction are best seen by reference to Figs. 2, 3, 4, and 5, and in these figures the screws marked a and b repiesentthespiings similarly marked in Fig. I. c is an uninsulated screwpost in connection with frame F. It is designed to furnish a means for adapting the instrument to use on a metallic circuit, and by variations in the electrical connections, as shown in Figs. 2, 3, 4, 5, provides for either retaining or excluding the magnet from circuit according tothe existing or desired practice.

Figs. `2 and 3 show con nections for use where the instrument is normally located upon and forms part of a metallic circuit, the connections shown in Fig. 2 being so arranged that when a double contact-plug is inserted theA electro-magnet m will be cutout. In this case the circuit normally enters at j, passes to spring a, to spring Z, (a and bbeing in contact, as in Fig. 1,) through magnet m, to post c, to post k. When a double contact-plug is insert-ed contact is made between one point of the plug and the spring c, and between the other point of the plug and the socket q; circuit passes cia the elements j c t', connected circuit or instrumentt q c lc, thus excluding the magnet m.

In Fig. 3 connections are so varied that when the plug is inserted the magnet is retained in the metallic circuit.

In Figs. 4 and 5 the connections are varied to adapt the instrument to use upon aground return-line. In the tirst instance the magnet is excluded from circuit upon introducing the single conductor-plug P. In the second instance, the magnet remains in circuit during the process of conversation. f

It is to be noticed that this adaptation of the instrument to single or double conductor-circuits and its adaptation to an arrangement of electrical connections, which either excludes or includes the magnet upon the introduction of ajack-plug, is due to the use of two insulated screw-posts or plug-sockets with an uninsulated post.

W`hat I claim, and desire to secure by Letters Patent, is

l. In a spring-jack, a pair of separable-contact-points in position to make electrical con tact with the contact point orv points of an appropriate spring-jack plug, combined with one or more fixed plug-sockets electrically connected to the terminals of the instrument to receive the cord tips or pins forming the terminals of that main-line circuit of which the spiiug-jac.k is intended to normally form a part.

2. The combinationuipon one frame or base, of an indicating-instrument, anda spring-jack consisting of a pair of separable contactpoints, with one or more fixed plugsockets, electrically connected to the terminals of the instrument, which are adapted to receive cord tips or pins forming the terminals of that main-line circuit of which the said instrument is intended to normally form a part.

3. The combination, in one instrument, of an annunci-(ttor with a spring-jack having a pair ol' separable contact-points arranged to form the terminals of the metallic circuit which normally includes said contactpoints and the annunciator-magnet, a plug having two contact-points making electrical contact with the terminals of the metallic circuit, and electrical connections, substantiall;T as described, so arranged that the insertion of the plug removes the magnet from circuit THOMAS B. DOOLITTLE.

`illitnesscs:

WM. B. VANsizn. GEO. ViLLIs Pinnen. 

